[U-Boot] [PATCH] pxe: Allow use of environment variables in append string

[U-Boot] [PATCH] pxe: Allow use of environment variables in append string

[Hans de Goede]

Use run_command("setenv bootargs <label->append>") so that environment
variables (e.g. $console) can be used in append strings.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 common/cmd_pxe.c | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/common/cmd_pxe.c b/common/cmd_pxe.c
index ba48692..3866604 100644
--- a/common/cmd_pxe.c
+++ b/common/cmd_pxe.c
@@ -571,14 +571,23 @@ static void label_print(void *data)
 static int label_localboot(struct pxe_label *label)
 {
 	char *localcmd;
+	char *bootargs;
 
 	localcmd = from_env("localcmd");
 
 	if (!localcmd)
 		return -ENOENT;
 
-	if (label->append)
-		setenv("bootargs", label->append);
+	if (label->append) {
+		bootargs = malloc(strlen("setenv bootargs ") +
+				  strlen(label->append) + 1);
+		if (!bootargs)
+			return 1;
+		strcpy(bootargs, "setenv bootargs ");
+		strcat(bootargs, label->append);
+		run_command(bootargs, 0);
+		free(bootargs);
+	}
 
 	debug("running: %s\n", localcmd);
 
@@ -669,17 +678,17 @@ static int label_boot(cmd_tbl_t *cmdtp, struct pxe_label *label)
 		len += strlen(label->append);
 
 	if (len) {
-		bootargs = malloc(len + 1);
+		bootargs = malloc(strlen("setenv bootargs ") + len + 1);
 		if (!bootargs)
 			return 1;
-		bootargs[0] = '\0';
+		strcpy(bootargs, "setenv bootargs ");
 		if (label->append)
-			strcpy(bootargs, label->append);
+			strcat(bootargs, label->append);
 		strcat(bootargs, ip_str);
 		strcat(bootargs, mac_str);
 
-		setenv("bootargs", bootargs);
-		printf("append: %s\n", bootargs);
+		run_command(bootargs, 0);
+		printf("append: %s\n", getenv("bootargs"));
 
 		free(bootargs);
 	}
-- 
2.0.3

[U-Boot] [PATCH] pxe: Allow use of environment variables in append string

[Stephen Warren]

On 08/01/2014 03:21 AM, Hans de Goede wrote:
> Use run_command("setenv bootargs <label->append>") so that environment
> variables (e.g. $console) can be used in append strings.

I'm slightly worried that this changes the semantics of the append line 
in the PXE/extlinux config file. Namely, you suddenly have to start 
worrying about escaping any $ signs or semi-colons etc..

> diff --git a/common/cmd_pxe.c b/common/cmd_pxe.c

>   	if (!localcmd)
>   		return -ENOENT;
>
> -	if (label->append)
> -		setenv("bootargs", label->append);
> +	if (label->append) {
> +		bootargs = malloc(strlen("setenv bootargs ") +
> +				  strlen(label->append) + 1);
> +		if (!bootargs)
> +			return 1;

Shouldn't this return a -ve error code for consistency with the other 
pre-existing error case I quoted above.

> +		strcpy(bootargs, "setenv bootargs ");
> +		strcat(bootargs, label->append);
> +		run_command(bootargs, 0);

Using whatever C function that the shell uses to expand variable 
references in the command-line, rather than run_command(), would at 
least avoid the issue of ; in label->append causing part of 
label->append after the ; to be execututed as a separate command.

There would still be the issue of $ suddenly meaning something different.

[U-Boot] [PATCH] pxe: Allow use of environment variables in append string

[Hans de Goede]

Hi,

On 08/01/2014 09:07 PM, Stephen Warren wrote:
> On 08/01/2014 03:21 AM, Hans de Goede wrote:
>> Use run_command("setenv bootargs <label->append>") so that environment
>> variables (e.g. $console) can be used in append strings.
> 
> I'm slightly worried that this changes the semantics of the append line in the PXE/extlinux config file. Namely, you suddenly have to start worrying about escaping any $ signs or semi-colons etc..

I'm not that worried about $ needing escaping, as I cannot think
of any kernel commandline options using $, maybe they exist but if
they do they are quite rare.

But you make a good point about the ; I know some kernel cmdline
options which use those...

> 
>> diff --git a/common/cmd_pxe.c b/common/cmd_pxe.c
> 
>>       if (!localcmd)
>>           return -ENOENT;
>>
>> -    if (label->append)
>> -        setenv("bootargs", label->append);
>> +    if (label->append) {
>> +        bootargs = malloc(strlen("setenv bootargs ") +
>> +                  strlen(label->append) + 1);
>> +        if (!bootargs)
>> +            return 1;
> 
> Shouldn't this return a -ve error code for consistency with the other pre-existing error case I quoted above.

Yeah this is weird, I copy pasted this from
the label_boot() function, of which is a special version,
also label_boot() is the only caller of label_localboot()
(where this hunk applies), and it does not check the return
value at all...

I could make it -ENOMEM if you prefer.


>> +        strcpy(bootargs, "setenv bootargs ");
>> +        strcat(bootargs, label->append);
>> +        run_command(bootargs, 0);
> 
> Using whatever C function that the shell uses to expand variable references in the command-line, rather than run_command(), would at least avoid the issue of ; in label->append causing part of label->append after the ; to be execututed as a separate command.

Ack, I'll look into that and post a v2 with that change.

> There would still be the issue of $ suddenly meaning something different.

Right, but as said I'm not really worried about that.

Regards,

Hans